1. Field of the Invention
The present invention relates to a probe in use with a pulse oximeter which measures an arterial blood oxygen saturation of a patient in a state that the probe is attached to a finger, toe or earlobe of the patient.
2. Related Art
A known probe of this type has a structure as shown in FIG. 14. A light emitting element 51 and a photo sensing element 52 are mounted on housings 53 and 54, respectively. The housings 53 and 54 may be turned about a shaft 55. The light emitting element 51 and the photo sensing element 52 are urged, by a spring (not shown), so as to be biased toward each other. The example illustrated is a probe designed so as to be attached to a finger of a patient or subject. In use, as shown in FIG. 14, the finger is inserted into a space and held between the housings 53 and 54.
The probe thus designed is advantageous in that its structure is simple and it is easy to the patient's finger to and remove it from the probe. However, the probe has the following disadvantages. In a case where what is to be set to the probe has a large individual variations, such as the finger, it is difficult for one probe to properly receive every sized finger for measurement. For example, the probe cannot properly receive the finger having a thickness of a predetermined value or larger. In this case, the finger, when set to the probe, is likely to shift from a correct position between the housings or to slip off. Further, an angle between the housings varies with the thickness of the finger inserted therebetween. Therefore, the optical axis of the light emitting element is misaligned with that of the photo sensing element. As a result, the measurement by the probe is instable.